Relief valve



Oct. 17, 1950 R. l.. RATHMANN RELIEF VALVE Filed Nov. 25, 1947 y INVENToR: P05522' 2mm/MAM BY ATTORNEYS.

Patented Oct. 17,` 1950 RELIEF VALVE Robert L. Rathmann, Tranquillity, Calif., assignor to Rathmann Implement, Tranquillity, Calif., a

firm

Application November 25, 1947, Serial No. 788,026

MyA invention relates to an oil lter system for hydraulic apparatus and is more speciically concerned with an attachment to be added to standard or well-known oil circulating systems for controlling heavy equipment, which makes possible the addition of a standard oil lter.

In most heavy road building equipment andA farming machinery wherein equipment is controlled by hydraulic cylinders which use oil pressure, it has been found that considerable expense and time must be spent incompletely overhauling and repairing the equipment because of the entry of dust and dirt into the oil supply.

The obvious solution to such a problem is by the addition of a filter for removing such dust and dirt. However, due to operating pressures involved in heavy road building and farming equipment, it has heretofore been impractical or impossible to use such oil filtering equipment.

It is an object of my invention to provide an oil liltering system whereby standard oil ltei's can be employed without danger ofA rupture bey cause of excessive pressures.

It is a further object of my invention to pro'- vide a means for by-passing excessive pressure around a filter so that it will be impossible for excessive pressure to be built-up in the iilter.

It is also among the objects of my yinvention to provide a simple attachment which can be applied to standard oil pressure systems for operating heavy equipment which will permit the use of a lter, thereby prolonging the effective life of the equipment and reducing the cost of eX- pensive repairs.

Other and further objects and advantages of 'my .invention will become apparent from the drawings and specifications relative thereto.

In the drawings: v

Figure 1 shows a standard oil pressure system having my invention added thereto.

Figure 2 isa detail cross-section of the by-pass means taken on line 2-2 of-Figure l.

Figure 3 is a sectional view taken on lline 3-3 of Figure 2. l

Figure 4 is a schematic diagram illustrating the fluid flow in my invention.

In the drawings, Figure 1 illustrates a wellknown hydraulic system which comprises .a uid reservoir tank I0, having an outlet conduit II communicating with a pump I2, and a pump discharge conduit I3 communicating with a directional valve I4. Conduits I5 and I6 communicate with the interior of the valve I4 and also with the hydraulic piston to be operated by the iiuid pressure. Further details of the internal 3 Claims. (Cl. 137-53) 2 connections will become apparent in an explanation of Figure 4.

The directional valve I4 is also formed with a mounting flange I3 adapted to mount the valve to the tank IIJ. The flange I9 is formed with a central bore adapted to communicate with the interior of the valve I4.

The parts described up to this point constitute standard equipment and are no part of my invention. My invention resides in the addition of a by-pass valve, designated generally 30, which comprises a cylindrical housing 3| dening a chamber 32. The upper portion of the housing 3| is internally threaded, as at 33, and a plug or cap 34 is threadedly disposed therein. The plug 34 is formed with an axial bore 35 adapted to receive the valve stem 36.

Whereas, I have herein illustrated the means for closing the top of the housing 3| as a plug, such as 34, it will become apparent that-the prin cipal function of such member is to position the stem 36 and to act as a backing for a compression spring 3'I. Any member which will perform this function should be considered an equivalent. Other devices which could be substituted might include a plate welded to the top of the housing 3| and could be either solid or could assume the form of a spider bracket.

' means 'of a threaded connection 42.

The lower extremity of the housing 3| is formed with a plurality of perforated sections 40, which, as will be seen, act as oil passages when the by-pass mechanism 36 functions to relieve pressure. A valve 4| is slidably disposed in the chamber 32 and is attached to the stem 36 by The spring 3l is adapted to press against the top of the valve 4i' urging it in a downward direction in fluidtight engagement against a plate 43; The plate 43 is Vformed with a bore 44 adapted to register with the bore 20 for the passage of oil or other hydraulic fluid and is interposed between the cation with the bore 50 by means of the iitting 52 and communicates with a filter 54. The filter 54 is vof more or less standard construction and is provided with a discharge 55 which communicates with the discharge line II from the voil tank by means of a conduit 56.

A reference to Figure 4 will clarify the manner in which my invention operates. The valve I4 comprises a four-Way valve having an inlet Illa and discharge ports |419, Ille and Md. A centrally disposed core or plug Si) is formed with passageways 6| and 62, As shown in the schematic illustration, the passageway 6| communicates between the ports Md and |40. The passageway 62 communicates between the ports |411 and Mb so that the flow of fluid is as follows: Commencing with the pump I2, fluid is forced under pressure through the line |3, passageway 62, conduit i6 and into a hydraulic cylinder 65, thereby forcing a piston 66 and piston rod 61 to the left. Fluid which is held in the cylinder to the left of the piston 60, is forced through the line I5, passageway 6|, passageway 29a, conduit 53, into the filter 54, thence out of the filter 54 through the line 56, into the conduit and returned to the pump I2. However, should the pressure in the passageway 29a exceed the setting of the relief valve 35, which will be determined by the structural limits of the lter 54, such excessive pressure will be by-passed through the pressure relief mechanism 3|] into the tank IU, thence out of the tank l0, through the conduit and back to the pump i2.

As will be readily understood, the spring 3"! (referring to Figure 2) will determine the amount of pressure against the bottom cf the valve 4|, which will cause the valve 4| to lift from sealing engagement with the plate 43, thereby permitting fluid to escape from the passageway 44 through the apertures l0 and into the tank i9.

Thus, it will be seen that I have provided a pressure relief system or attachment to be used in connection with standard hydraulic systems, which permits the use of filtering devices which will substantially clean the hydraulic ud used in the system, thereby preventing excessive wear on the pump and the hydraulic control pistons.

While I have herein shown and described my invention in what I have conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope of my invention, which is not to be limited to the details disclosed herein, but is to be accorded the full scope of the claims so as to embrace any and all equivalent devices.

Having described my invention, what I claim as new and desire to secure by Letters Patent is:

l. A pressure responsive valve adapted to provide stepped volumetric fluid ow therethrough in response to pressures imposed thereon comprising a hollow member having a cylindrical bore therethrough, a closed end portion, and an open end portion; a base member receiving the open end portion of the hollow member and circumscribing said member for an appreciable distance from the open end portion, said base member providing an annular seat concentric to the cylindrical bore of the hollow member, normal to the axis of said bore, and defining a, fluid supply bore concentrically of the annular seat; the hollow member being slotted from its open end portion to positions appreciably beyond the portion circumscribed by the base member; a valve mounted for slideable movement axially of the member between a position seated on the annular seat, a position retracted into the hollow member removed from the circumscribing portion of the base member; and a spring mounted under initial compression between the closed end of the hollow member and the valve whereby the valve is seated when pressures less than a predetermined magnitude are impressed thereon through the supply bore, pressures slightly in excess of the predetermined magnitude displace the valve from seat engagement for iiuid flow between the valve and the circumscribing base member longitudinally of the slots, and further increase of pressure further removes the valve from within the base member for direct fluid flow radially of the hollow member through the slots.

2. A by-pass valve comprising a base plate hav ing a flat surface, a supply bore formed therethrough normal to the at surface, and an exhaust bore formed in communication with the supply bore within the base plate, a mounting plate secured to the base plate in fluid tight engagement with the flat surface and having a counter bore formed therein concentrically of the supply bore; a hollow cylinder having spaced, annularly arranged, axially extended legs mounted in the counter bore of the mouting plate; a valve slideably mounted in the cylinder and legs for movement between a position seated on the flat surface of the base plate in covering relation to the supply bore and a position retracted in the cylinder spaced from the base plate; a stem mounted by the valve and axially extended relative to the cylinder; a closure member mounted in the cylinder opposite the valve from the base plate and slideably receiving the stem; and a spring positioned under initial compression between the valve and thel closure member.

3. In a lter system for hydraulic control systems, a by-pass valve comprising a base plate having a fiat upper surface, a fluid supply bore formed therethrough normal to the flat surface, and an exhaust bore formed in communication with the supply bore; a fluid reservoir having a mounting plate defining a bottom therefore secured to the base plate in fluid tight engagement with the fiat surface of the base plate and having a counter bore formed therein concentrically of the supply bore; a hollow cylinder having spaced, annularly arranged, axially extended legs mounted in the counter bore of the mounting plate inwardly of the reservoir; a valve slideably mounted in the cylinder and legs for movement between a position seated on the flat surface of the base plate in covering relation to the supply bore and a position retractedin the cylinder spaced from the base plate; a stem mounted by the valve and axially extended relative to the cylinder; a closure member mounted in the cylinder opposite the valve from the base plate and slideably receiving the stem; and a spring positioned under initial compression between the valve and the closure member.

\ ROBERT L, RATHMANN.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,020,774 Nilson Mar. 19, 1912 1,379,259 Hans May 24, 1921 2,242,807 Austin May 20, 1941 

